He urged the congress of the Party of European Socialists to 'work together to help build a real social Europe, a people's Europe, a Europe that will strengthen solidarity across borders, resist the race to the bottom in rights and protections and work together to extend them for all workers, consumers and our environment'.

So far, so good. Even the 'free market' fanatics of the European Commission might happily pay lip service to that. But the Labour leader continued:

'We have to recognise that European Union support for austerity and failed neoliberal economics have caused serious hardship for working people across Europe. In my own country there's been effectively a wage freeze for ten years. It's damaged the credibility of the European social model and social-democratic parties and played a significant role in the vote for Brexit in Britain'.

Some of the delegates from the social-democratic and 'socialist' parties of Germany, France, Italy, Greece, Cyprus, Ireland, Denmark, Sweden and the Netherlands should have squirmed at that point. Over recent decades, to a greater or lesser degree, they have all embraced neoliberal policies of public spending cuts, marketisation, privatisation, labour flexibility, higher taxes for the working class and lower taxes for the rich and big business.

They have doggedly upheld the European Union and its treaties which enshrine the EU's commitment to a capitalist market economy, the free movement of capital and super-exploited labour, monetarism, militarisation and alignment with NATO.

They have all utterly failed to combat the austerity policies inflicted on their own people by their own capitalist class and in some cases by the EU-Commission-EU Central Bank-IMF 'troika'.

And they have all been severely punished by millions of working-class electors who have either turned in fear or anger to what Corbyn called the 'fake populists of the far right', or moved to the left, or stopped voting altogether.

Last year, the German SPD saw its share of the poll in parliamentary elections fall to an all-time low of 21 per cent. Since breaking a solemn manifesto pledge not to continue in coalition with Angela Merkel's Christian Democrats, the SPD vote has been further cut in state elections this year by half to 10 per cent in Bavaria and by one-third to 21 per cent in Hesse.

The biggest winners in recent German elections are the far-right, nationalist Alternative for Germany and the unprincipled Greens.

In France, electoral support for the misnamed Socialist Party has been downsized by its defecting spawn to the right and the left, namely, President Macron and Jean-Luc Melenchon. Four-fifths of the party's voters went walkabout in last year's national assembly elections and again in the first round of the presidentials this April.

The Democratic Party in Italy has been loyally pro-EU and pro-austerity, losing almost half of its popular vote since the 2008 crash as a result. The country is now governed by a Eurosceptic coalition of the far-right League and Forza Italia parties and the eclectic Five Star Movement. Backed by the financial markets, the EU Commission and the European Central Bank are demanding that the coalition drop its plans for a deficit budget that will benefit the unemployed and the elderly.

In Greece, the Netherlands, Cyprus and the Czech Republic, the social-democratic parties' percentage share of the poll has been slashed to single figures.

Austria, Sweden, Denmark and to a lesser extent Spain are among the few EU member states where the traditional social-democratic parties retain substantial mass support.

In Portugal, the Socialists are in government thanks to support from the anti-EU Communist Party and the increasingly Eurosceptic Left Bloc. Indeed, Corbyn made a point in his Lisbon speech of congratulating all the parties of the Portuguese left on their unity.

The British Labour Party leader had another important message for the congress. In case any delegates rely on the Guardian or the BBC for an analysis of the public mood in Britain, he implored them:

'Please understand that those people that voted for Brexit ... voted because they were angry at the situation they were in, with frozen wages, poor working conditions and a sense that their communities that had lost their industries have been left behind. There are places like that all over Europe, where people feel angry at the economic failure to provide hope, particularly for the young generation'.

That's a different picture to the one painted by so many EU enthusiasts in Britain: that we are home to 17.4 million undereducated, racist simpletons who follow like children or rats behind Pied Pipers Boris Johnson, Michael Gove and Nigel Farage.

Then came Jeremy Corbyn's clear challenge to the congress:

'European socialists have to fight for a different kind of Europe. Our prize is a new, progressive economic consensus that breaks with the failed market dogmas of the past and secures shared prosperity built on a powerful public realm. We must build a new Europe - both inside and outside the institutions of the European Union - that really does work for the many, not the few'.

He reminded delegates that Labour's stance in the 2016 referendum campaign had been to remain in the EU and help to reform it, to 'shift the EU towards a more genuinely social Europe, to help loosen the corporate grip on the EU's agenda and reform some of the more restrictive market-driven regulations that exist in Europe'.

Although Corbyn repeated his view that Labour must now respect the majority decision to leave the EU, that 'Remain and Reform' perspective is being revived in some labour movement circles.

It raises profound questions of practicality and strategy, as well as democracy.

Firstly, what agreement could be reached about the reforms to be pursued?

Should the two basic EU treaties be rewritten to end the primacy of the so-called 'competitive free market', or to limit the free movement of capital and labour? What about the corporate right of establishment, which the EU Court of Justice has used to negate the rights of workers, trade unions and elected governments? Should the EU ban, in effect, on 'people's quantitative easing' be abolished?

How can the extraordinary powers of the EU Commission be devolved to member states, or democratised without handing them to a European Parliament which has no real organic link with its 396m electorate, with one MEP per half a million electors? What about the unaccountable powers of the European Central Bank and the absurdity of a one-size-fits-all euro? Should the monetarist restrictions on members state borrowing and debt be relaxed or abolished? What should be done about VAT?

Assuming agreement on a reform programme, who will fight for it against the entrenched opposition of the mainstream right-wing parties, employers' organisations and senior state apparatchiks across most of the EU?

The enfeebled, vacillating and mostly pro-big business social-democratic parties of Europe? The Green parties, most of which dump their anti-market, anti-monopoly, anti-militarist policies at the first whiff of government office?

The anti-EU or Eurosceptic left in the Communist parties and formations such as the Left Bloc (Portugal), Podemos (Spain), Die Linke (Germany), the Swedish Left Party, the Danish Red-Green Alliance and Melenchon's movement? These either regard the EU - with good reason - as unreformable or they are not strong enough to win general elections.

Reforming the EU on the scale required to turn it away from today's 'Big Business Europe' towards tomorrow's 'People's Europe' would necessitate the election and re-election of left, reforming governments in most of the major member states and many of the minor ones within the same time-frame.

That is a far more remote prospect than electing a left-led Labour government here in Britain.

Winning such a government requires a General Election. Securing the freedom for such a government to implement policies of public investment, public ownership, economic and environmental planning, progressive taxation and full workers' and trade union rights requires a People's Brexit from the EU and its Single Market and Customs Union rules.

Make no mistake, a second referendum to keep Britain in the EU is intended by its political and financial backers to abort any such breakthrough.